Aptamer-Based Label-Free Colorimetric Assay Using Gold Nanoparticles for Specific Detection of Streptococcus suis

Area of Science:

• Nanotechnology
• Biosensing
• Microbiology

Background:

• Streptococcus suis is a significant zoonotic pathogen causing severe infections in humans and pigs.
• Current identification methods for S. suis are limited, necessitating faster and more accessible diagnostic tools.

Purpose of the Study:

• To develop a simple, rapid, and cost-effective label-free colorimetric aptasensor for detecting Streptococcus suis.
• To evaluate the specificity, sensitivity, and reactivity of the aptasensor with various bacterial species and S. suis serotypes.

Main Methods:

• A label-free colorimetric assay utilizing gold nanoparticles (AuNPs) functionalized with a specific aptamer (R8-su12).
• Visual detection via color change and quantitative assessment using UV-Vis spectrophotometry.
• Testing against a panel of bacterial species and clinical S. suis isolates.

Main Results:

• The aptasensor achieved detection within 45 minutes under optimal conditions.
• High specificity was demonstrated, with no cross-reactivity observed against other tested bacterial species.
• A limit of detection (LOD) of 1 CFU for S. suis was achieved, with broad reactivity across multiple serotypes and clinical isolates.

Conclusions:

• The developed aptasensor is a promising tool for the early screening and management of Streptococcus suis infections.
• Its simplicity, speed, and cost-effectiveness make it suitable for diverse settings including clinical labs, food safety, and environmental monitoring.